Frank m



F. M. FOSTER.

IGNITION SWITCH.

APPLICATION FILED APR. 10. 1920.

Patented Apr. 12, 1921..

IN VEN TOR.

A TTOR E YS.

UNITED STATES FRANK M. FOSTER, OF WASHINGTON, DISTRICT OF COLUMBIA.

, IGNITION-SWITCH.

Specification of Letters Patent. Pate t d Apr, 12 1 2 Application filed April 10, 1920. Serial No. 372,842.

To all whom it may concern Be it known that I, FRANK M. F os'rnn, a citizen of the United States, residing at lVashington, in the District of Columbia, have invented certain new and useful Improvements in Ignition-Switches, of which the following is a specification.

My invention relates to electric ignition systems for internal combustion engines, and more particularly to improved switching means for controlling the circuits of such a system where both a generator and storage battery are employed.

In certain types of machines, as for example, in aeroplane motor equipment, good practice often prohibits the use of a reverse current relay or cut-out between the generator and storage battery, so that, in such a system, there is nothing to prevent the battery from discharging back through the generator under certain conditions, and this frequently produces disastrous results.

In certain well known makes of high speed aeroplane motors, it is the usual practice to provide two separate and independent ignition systems including two spark plugs for each cylinder, two coils, and two distributers. Switches are provided, by means of which either one or the other or both spark coils can be connected with the battery, and the generator connected with these elements in multiple, or disconnected entirely' therefrom. It is intended that the generator shall be connected to the battery only after it has reached a predetermined critical speed, but it has been found in practice that, due to careless or improper manipulation of the switches, trouble has frequently been caused by connecting the generator in circuit, before its voltage is sufficiently high, or permitting it to remain in circuit after its voltage has fallen too low. In either case, the result is that the battery discharges through the generator, thus not only exhausting the battery, but frequently damaging the gen erator windings, so that they become open circuited or short circuited, and thus' entirely deprive the ignition devices of current. Many 'forced landings of aviators have been due to this cause.

It is, therefore, the object of the present invention, broadly, to provide means, whereby upon the occurrence of a flow of current in the reverse direction, due to short circuit or other causes, the generator may be ent rely disconnected from the circuit while maintaining the connection between the battery and ignition device. cally, the invention seeks to provide improved switching means in combination with a duplex ignition system, such as described, so arranged that in case of accident to the generator 1t may be entirely disconnected from the circuit, while at the same time the battery may be caused to supply current to both ignition devices, and thus enable the motor to continue in operation.

In order that the invention may be readily understood, reference is had to the accompanying drawings forming part of this spec fication, and in which,

Flgure 1 is a diagram showing the circuit connectlons of a duplex ignition system embodying my invention F1gs. 2, 3 and 4 are fragmentary elevatlons on an enlarged scale showing my improved switch in its three different positions;

Fig. 5 is a rear view of the switch member, parts being broken away, and

Fig. 6 is a central longitudinal section therethrough.

I eferring to the drawings in detail, the lgnition system illustrated in Fig. 1 is of a well known type and comprises a switch box X in which is formed an opening A for the reception of an ammeter. B represents the storage battery, C and C the two spark coils, and D the dynamo or generator. which is driven from the engine. 03 and d diagrammatically represent the two distribu-' ters connected respectively to the spark coils C and C, and S and S designate in their entirety a pair of switches employed to control the various circuits, as will hereinafter appear.

Each of these switches comprise a handle a, and an insulating hub b, carrying the contact arms. Swith S, as heretofore constructed, comprises two pairs'of arms 27, 28 and 29, 30, insulated from each other as by means of an insulating washer 0 (see Figs. 5 and 6). The switch S comprises asingle member having four arms, all electrically connected. three of these arms, namely, 24, 25 and 26 being operative and the fourth being idle.

The switch S is provided with four contacts preferably arranged in diametrically More specifiopposite pairs 3, 4 and 13, 14, while the switch S is provided with three contacts, namely, 6, 7 and 11, preferably arranged 90 and 180 apart, as shown in Fig. 1. In this figure the full lines represent the switches in their off or inoperative position, while the dotted lines show the switches in their on or operative position.

Without further description of the construction, it is thought that an understanding of the system will be clear from a brief statement of its operation.

Normally when the machine is at rest, the switches are in their full line positionv When it is desired to start the motor, either one switch or the other is thrown into its dotted line position, and by this means either one spark coil or the other is connected to the battery. If the switch S is thrown to dotted line position, current from the battery will flow over the line 21, binding post 20, connection 00 (representing the ammeter) binding post 19, conductors 18, and 12 to contact 13, thence or er the arms 30 and 29 to contact 14, thence over wire 15 through the primary winding of coil C, through conductor 16 to ground. This operates the coil and the high voltage current from the secondary is delivered over the wire 17 to the distributer d.

If the switch S be thrown to dotted line position, current fromthe battery will pass from conductor 18 as above, and thence; from contact 11 through arms 26 and 24 to contact 7, whence it will flow over wire 8 through the primary winding of coil C and thence over wire 9 to ground. This generates current in the secondary winding, which is delivered by the wire 10 to the distributer cl.

Thus it will be seen that the operator can use either one of the ignition devices on starting, and can switch from one to the other at will. He .must not, however, attempt to throw both switches to the on or dotted line position, as this would resultin prematurely connecting the generator to the battery. Assuming, however, that the motor and generator have reached the necessary predetermined speed, both switches can be thrown to the on position, and current will then flow from the generator D over conductor 1, wire 2 to contact 3, thence over arms 27 and 28 to contact 4, thence over wire 5 to contact 6, from which point it divides, part flowing by way of arms 25 and 24 to contact 7 and conductor 8 to the coil C and another part going byway of the arm 26 to contact 11. From this point also the current divides, part flowing over the wire 12, contact 13, arms 30 and 29, contact 14 and wire 15 to coil C, and the other part following conductors 18 and 21 to the battery B and thence to ground. The battery is preferably arranged in two sections,

which may be connected by a switch 22 as shown, and having a common ground conn'ection 23.

Thus when the machine is in normal operation, current is supplied from the genera tor for operating both ignition devices, and for charging the battery, all three of these elements being connected in multiple or parallel.

The system as so far described is well known. The defect in it, however, is that should both switches be thrown into opera tive position too quickly, or should they be allowed to remain in such position if the motor slows down below a critical speed, the battery will discharge back through the generator. This, of course, can be stopped, as soon as it is observed, by throwing one switch or the other back to full-line position, but by so doing, the corresponding ignition device is also disconnected from the battery and rendered inoperative. For example, it is obvious from an inspection of Fig. 1 that when the switch S is in full-line position, the generator circuit is interrupted at the contact 3, but it will also be noted that the ignition circuit is likewise opened at contact 14 and the corresponding distributer deprived of current.

In aviation work, particularly, it is especially desirable to maintain both ignition devices in operation, so as to insure perfect working of the motor, and I have devised means whereby this canbe accomplished. Referring to Figs. 2 and 5, I propose to provide the switch S with an auxiliary pair of arms 33, 34, carried by a central disk 32, insulated from the corresponding disk 31. carrying the arms 29 and 30, by means of an insulating washer 0. In the embodiment shown, the arms 27, 28 and 29, 30 are'placed at substantial right angles to each other. while my auxiliary arms are preferably set at an angle of substantially 223 to the arms 27 and 28. I contemplate throwing my improved switch to three positions. The first is the normal off position shown in Fig. 2. 1n which all ofjthe arms are out of engage-- ment with all of the contacts. The second or on position is shown in Fig. 3, and in this it will be noted that the usual arms 27, 28 and 29, 30 are in engagement with the contacts 3, 4 and 13, 14 as described in connec tion with the dotted line position of Fig. 1. The third or emergency position of my improved switch is shown in Fig. 4, and in this position it will be noted that the contacts 13, 14 are engaged and bridged by the auxiliary arms 33, 34, while all four of the other arms are entirely out of engagement with the contacts. The result of this is that when the switch S is thrown to the emcr-- gency position, as shown in Fig. 4, the gen erator is entirely disconnected, but the battery can supply current to coil C over con-- tacts 13, 14 and the auxiliary arms of the switch, so that, if switch S is also in dotted line position, both ignition devices can receive current from the battery, thus insuring regular operation of the motor.

In practice, the switch S should be thrown to this emergency position either at starting, or when gliding, or when, for any other reason, the generator voltage is below the critical point. It will, of course, also be thrown to this position in case of damage to the generator at any time.

In switches of the above type, having resilient arms, it is usual to provide the face of the box X with depressions 35, into which the ends of the arms snap, as the switch is moved froinwne position to another. In order to avoid two steps or notches, and to cause the switch to move smoothly from on to off position, I preferably provide arc shaped grooves 36 adjacent the contacts 3 and 4, instead of the depressions 35, as will be obvious from an inspection of Figs. 2,3 and 4.

It will thus be seen that I have provided a construction whereby well known ignition systems in common use may be equipped with means for cuttingout the generator and for connecting the battery to one or both ignition devices, without the use of any additional switch, circuits, or other complications,-and it is thought that the simplicity, efiectiveness, and many advantages of my improved construction will be readily appreciated by those skilled in the art.

' What I claim is:

l. The combination with r a generator, storage battery, and ignition device, of a pair of mechanically independent switches arranged to electrically cooperate to connect the generator with the battery and ignition device, means whereby the generator connection may be broken by moving either switch, and meansv whereby one of said switchesmay connect the battery and ignition device only.

2. The combination with a generator, battery, and two independent ignition devices, of a pair of switches arranged in cooperative relation to connect the generator with the battery and both ignition devices, means whereby the generator connection may be broken b either. switch, and means whereby both switches may be caused to cooperate to connect the battery with both ignition devices, with the generator entirely disconnected.

3. The combination with a generator, storage battery, and ignition device, of a switch having one contact connected with the generator one with the ignition. device, and two with the storage battery, said switch being provided with two pair of arms insulated from each other, and serving, when the switch is in in position, to engage all of said contacts and thus connect the generator with both the battery and ignition evice, and said switch having a third pair of arms, serving when the switch is in another position, to engage two of said contacts only, and thus connect the battery with the ignition device, while disconnecting the generator.

4. The combination with a generator, storage battery, and ignition device, of a pair of switches, both together, when in one position, serving to connect the generator with the battery and ignition devlce, either of said switches, when moved to another position, servin to disconnect the generator, and one of said switches serving, when in a third position, to connect the battery and ignition device.

5. The combination with a generator, storage battery, and ignition device, of a pair of switches, both together, when in one position, serving to connect the generator with the batter and ignition device, means whereb one 0 said switches, when moved to another position, serves to disconnect the generator, and the other of said switches, when moved to another position, serves to disconnect both batter and generator from the ignition device an from each other, and means whereby said last mentioned switch, when moved to a third position, serves to corlinect the ignition device with the battery on y.

6. The combination with a enerator, storage battery, and two independent ignition devices, of a pair of switches, both to gether serving when in one position, to connect the generator with the battery and both ignition devices, means whereby either switch, when moved to another position, serves to disconnect the'battery from the generator and also from the respective ignition device, and means whereby one of said switches, when moved to a third osition, serves to connect the batter with t e corres onding ignition device, w ile maintaining t e generator disconnected from all of the other apparatus.

7. The combination with a generator, storage battery, and two independent ignition devices, of a pair of switches, both together serving, when in one position, to connect the generator with the battery and both ignition devices, means whereby either switch when moved to another osition, serves to disconnect the battery m the generator and also from the respective ignition device, and means whereby, when one of said switches is moved to a third position,

and the other switch kept in the first mentioned position, the battery will be connected to both ignition devices, with the generator entirel cut out of circuit.

In testimony w ereof I afiix m si ature. FRANK M. I O 

